Control switch



Feb. 17, A1942.

B. E. SHAW CONTROL SWITCH Filed Nov. 4, 1940 v INVENTOR. ,BY WZiOw/ZQZZ/ gm QGQ/wm/ 4Parental Feb. 17, 1942' CONTROL SWITCH Burton E. Shaw, Bristol, 1nd., assigner to Penn Electric Switch Co., Goshen, Ind., a corporation of Iowa Application November 4, 1940, Serial No. 364,269

(Cl. 20o-139) l16 Claims.

My .present invention relates tol a control switch, particularly one of the kind adapted to respond to temperature of a surface to which the switch is attached.

One object or" the invention is to provide a compact switch structure adapted to control voltages of 110 or 22o, with the parts of the switch comparatively simple and inexpensive to manufacture and install.

Another object is to provide a surface switch having a temperature responsive element that is isolated from the body of the switch by an insulating base member and enclosed within a metallic housing having parts in contact with a steam or hot` water pipe` to facilitate transmission of heat from the pipe surface to the temperature responsive element oi? the switch, the switch being thereby quickly and accurately responsive to such heat.

Another object is to provide a switch structure wherein compactness is secured by designing a base member having a central hub for an adjusting shaft of a coiled bimetallic element with a conduit connection mounted on one side of the hub and the switch mechanism mounted on the other side, terminals for the wires of the conduit being mounted on opposite sides of the hub and between the switch and conduit tting.

Still a further object is to provide a bracket for the conduit iitting which serves also as a stop for an adjusting knob and as a'means to which the cover is secured.

A further object is to provide a switch structure which may b e mounted in any position, yet has a dial which is readily readable for setting the range of operation.

With these and other objects in View, my invention consists in the construction, arrangement and combination of the various parts of my device whereby the objectsy contemplated are attained, as hereinaiterA more fully set forth, pointed out in my claims and illustrated in the accompanying drawing- Although the invention is susceptible oi a variety of embodiments, it is unnecessary to fully describe and illustrate more than one in `order to givre` a full understanding of the inventionboth fr om its structural and functional standpoints. Accordingly, I have '11- lustrated a preferred and desirable embodiment .of the invention in the accompanying drawing,

in which:

y Figure 1 is a perspective view of my control switch showing it mounted on a steam pipe lor the like; A s v y i Figure 2 is a horizontal sectional view as taxen on the line 2--2 ci Figure i;

Figures 3, i and 5 are vertical sectional views taken on the lines 3 3, il-ll and 5 5, respec tively, of Figure 2; and

Figure tis a bottom plan view of the control switch with a portion oi one of the plates broken away to show constructional features.

On the accompanying drawing, I have used the reference character B to indicate in general a base member and C a cover therefor. The members B and C are preferably of insulating material. The base member B has a recess I0 in its bottom surface into which a depressed part l2 of a first base plate I3 extends. A second base plate i4 is provided with extensions l5 which are shaped to lit the surface of a pipe I6. The extensions l5 are `secured to the pipe I6 and held tightly in thermal contact therewith by a Y pair of clamp bands Il.

The base member B has a central hub I8 through which an adjusting shaft i9 rotatably extends. The shaft i9 has a head 20 within a temperature responsive element housing formed by the base plate lll and the upwardly depressed portion l2 of the base plate i3. The head 20 is slotted as at 2l to receive one end of a coiled bimetal element 22.

20 frictionally engages the base plate i4 under `the bias of a spring friction washer 23 located between the head 20 and the portion i2 ci the base'plate i3. The lower end of the adjusting shaft I9 is journaled in a perforation 24 of the base plate it.

spaced from the hub it on one side of the shaft i9 is an upward projection 25 from the base member B. A bracketv 26 extends upwardly from the other side oi the base member, the bracket being secured to the base member by screws 2l passing through ears to of the bracket and threaded into the base member. The

bracket 2t is bent L-shaped and is provided with an opening 2@ to rotatably receive the adjusting shaft t9. Beyond the adjusting shaft the bracket has an upwardly extending stop lug 3o. An ad- -justing knob 3G is mounted on the shaft I9 as by a set screw 32 and has an arcuate groove 33 receiving the stop lug till. The groove 33, as shown by dotted lines in Figure 2, limits the rotation of the adjusting knob 3i to substantially 180.

The cover C is mounted on the base B and retained in position thereon by a pair of screws 3i and 35 extending into the bracket 26 and the projection 25, respectively. The cover is pro- The lower end of the head La permanent horseshoe magnet 4l yis provided to impart snap action thereto. rlhe magnet lll is retained in a socket I2 of the base member B by a screw 43. The switch arm 38 carries a substantially straight leaf spring M having thereon a movable contact 55. The leaf spring is anohored at one end to the switch arm by a screw I6 and at its other end extends through a slot I1 which permits limited lost motion of the leaf spring relative to the switch arm.

A stationary contact I8 is carried by a difierential adjusting screw l! which in turn is threaded through a supporting plate 50. The supporting plate 50 has one end mounted on one oi' the hub extensions I8 by a terminal screw 5| and its other end mounted on a lateral extension 25* of the proiection 25 as by a rivet or the like 52. An adjusting knob 53 is mounted on the screw A9 and cooperates with a-dial 5I formed on the mounting plate 50. f

A second terminal screw 55 is mounted on the other extension i8* and it is connected by a pigtail 55 to a bracket 51 secured in position on the switch arm 38 by the screw 48. The bracket 2B is adapted to support a conduit fitting 58 into which a conduit 59 extends. The electric wires 60 in the conduit connect with the respectiveterminals 5i and 55.

To provide an operative connection between the coiled bimetal 22 and the switch arm 38, I provide an actuating arm 6| formed preferably of insulating material and secured as by a screw 82 to the switch arm 38 as shown in Figure 5. The lower end of the actuating arm 5| has a seat 53 for a thrust blade 8l on the free end of the birnetai element 22 to give a knife edge bearing at this point. To retain the bearing elements in contact, a. finger 65 extends from the thev actuating blade il and partially encircles arm 8|. To accommodate the actuating arm 5I A'and the necessary movement thereof, the base member B is provided with an opening land the base plate I3 is provided with an opening Gib.

Cooperating with the adjusting knob IL-I provide a dial plate I5 having a pair of indicating scales 01 and I8 thereon. The knob ll has a pair of pointers B9 and 10 cooperating with the respective scales 81 and 5B. The scales are arranged double in the manner illustrated in Iiig ure 1 so that the control switchV can be mounted with the conduit 5! extendingeither to the right or to' the left. In one .of these positions, one of the` scales is readily readable inconjunction with the adjusting knob, while in the other position the other scale would'be used. J

Thebase plates I3 and Il are secured in position as by countersunk screws 1I as shown yin Fig- The screws 1| extend through keyhole type openings 12 in the base plate Il and through enlarged openings 'Il in the baseV plate Il. The

' keyhole openings are arranged so that the screws can be loosened and the base plate Il rotated slightly and then removed for access to the bimetal element 2i.

aavassi Practical operation My control switch is particularly adapted to be installed in series with an oil burner motor so as to act as a limit switch for a steam or hot water heating system. iibviously. it is adaptable for use wherever temperature response is desired, with the temperature taken from. the surface of a pipe or the like. Normally the switch is closed as shown in Figure 5. The knob 3i is adjusted for the desired temperature range so that when the temperature setting is reached the switch will cut out. A rise in temperature causes the birnetal coil t2 to contract, thereby swinging the actuating lever ti oi Figure 5 in a left hand direction. Due to the attraction of. the magnet ll iior the switch arm 38, tension will be built up in the bimetal element 22 until such tension overcomes the pull of the magnet, whereupon the actuating arm 5| will quickly swing toward the left, thus lowering the right hand end of the switch arm 38 in Figure 5. Such movement will nrst bring the upper edge of the lost motion opening 41 into contact with the top of the leaf spring il! and then the leaf spring will move with the switch arm and separate the contact 'l5 from the contact i8.

lis the temperature in the pipe l5 recedes, it will eventually expand the coiled bimetal element '.22 until ,it swings the switch arm 38 to a position where the magnet I will snap it to closed position. The diiferential of operation or number of degrees difference between cut-out and cut-in of the switch may be adjusted by the adjusting screw 9 which predetermines the distance of the switch arm 38 from the magnet Il in the closed circuit position of the switch. The smaller such distance, the greater will bethe diilerential of operation.

The arrangement of parts is such that a very compact switch is the result. The switch, though designedfor heavy currents, is quite small, as shown on the drawing wherein Figures 2 to 6 are drawn full size. The arrangement of the switch mechanism on one side of the hub Il and the conduit fitting 5B on the other side, with the switch terminals 5i and 55 on opposite sides of the adjusting shaft i9 and the shaft being centrally located, all contribute to compactness of design.

Some changes may be made in the construction and arrangement of the parts of my device without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope without sacrificing any of the advantages thereof.

' I claim as my invention:

1. In a control switch, a base member of insulating material having a recessed portion in its lower surface, a pair of base plates secured to the bottom of said member, one of said base plates having a depressed portion entering said `recess to form a temperature responsive element sive element, a. switch on said base member having anactuating element extending into such housing, an operative connection betweensaid temperature responsive element and said actuating element, a cover of insulating material for said switch, said cover being mounted on said base member, said cover having an indicating dial thereon and a knob on said adjusting shaft cooperating with said indicating dial.

2. In a control switch, a base member, a pair-o base plates secured to the bottom thereof to form a temperature responsive element housing in conjunction with each other, a range adjusting shaft extending centrally downward through said base member and into such housing, a coiled bimetal element mounted on said shaft within said housing, means for securing one of said base plates to the surface of a pipe or the like to receive heat therefrom by conduction, and to transfer such heat by conduction through said plates and by conduction and radiation to said bimetal element, a switch on said base member having an actuating element extending into such housing, an operative connection between said bimetal element and said actuating element, a bracket secured to said base member, a conduit fitting connected therewith, said bracket having a perforation through which said adjusting shaft extends, said bracket beyond said shaft having an upturned stop portion, a knob on said shaft having an arcuate groove to receive said stop portion, said base member having a hub for said shaft and a projection spaced from said hub, said switch including a switch arm between said hub and said projection, a pivot pin for said switch arm having its ends mounted in said hub and said projection,` a cover on said base member for said switch, and mounting screws for said cover projecting into said bracket and projection.

3. In a control switch, a base member, a pair of base plates secured to the bottom thereof, one of said base plates being relatively dat, the other an actuating element extending into such housing, an operative connection between said bimetal liv element and said actuating element, and a cover for sai'd switch.

4. In a control switch of the character disclosed, a basemember having a central bore, a range adjusting shaft rotatable in said bore, a flat base plate and a base plate having an upwardly depressed part secured to the bottom of said base member and forming a temperature responsive element housing, said bottom of said base member having a recess therein to receive said part, said range adjusting shaft extending into such housing, a coiled bimetal element mounted on said shaft within said housing, a switch on said base member having an actuating element extending into such housing, an operative connection between said bimetal element and said actuating element, a cover for said -switch mounted on said base member, said cover having an intif) dicating dial thereon and a knob on said range adjusting shaft cooperating with said indicating dial.

5. In a control switch, a base memberl having a recessed portion in its lower surface, a pair of base plates, one of said base plates having a depressed portion entering said recess to form a temperature responsive element housing in conjunction With the other base plate, a range adjusting shaft extending downwardly through said base member and into such housing, a coiled bimetal element mounted on said shaft within such housing, means for securing ysuch housing to the surface of a pipe or the like to receive heat therefrom, a switch on said base member having an actuating element extending into such housing, an operative connection between said bimetal element and said actuating element, and a knob on an upturned stop portion, a knob on said shaft `having an arcuate groove to receive said stop portion, a cover on said base member for said switch, and a mounting screw for said cover projecting into said'bracket.

'7. In a control switch, a base member, a range adjusting shaft extending through said base member, a coiled bimetal element mounted on said shaft, a switch on said base member having an actuating element, an operative connection between said bimetal element and said actuating element, a bracket secured to said base member, a conduit fitting connected therewith, said bracket having a perforation in which said adjusting shaft is journaled, a knob on said shaft, said base member having a projection spaced from said shaft, a cover on said base member for said switch, and'mounting screws for said cover projecting into said bracket and projection.

'8. In a control switch, a base member, a pair of base plates secured to the bottom thereof to form, in conjunction with each other, a temperature responsive element housing, a range adjusting shaft, a coiled lbimetal elementJ mounted on said shaft within said housing, means for securing one of said base plates to the surface of a pipe or the like to receive heat therefrom, a switch on said base member having an actuating element extending into such housing, an operative connection between said bimetal element and said actuating element, said lbase member having a central bore for said adjusting shaft, said switch being mounted on one side of said shaft, a conduit; fitting mounted on the other side of said shaft, terminals for said switch mounted on opposite sides of said shaft between for cooperation with a pointer on said knob whereby said b ase member -may be installed in any desired position and thereafter readily read and adjusted.l

9. A control switch comprising a base member, a metallic temperature responsive element` housing thereon, a range adjusting shaft extending through said base member and into such housing, a coiled bimetal element mounted on said shaft within said housing, means for securing said housing to the surface of a pipe or the like to receive heat therefrom by conduction, a switch on said base plate having an actuating element eirtending into such housing, an operative connection between said bimetal element and said actuating element, a bracket secured to said base member, said bracket having a perforation through which said adjusting shaft extends, said base member having a hub for said shaft and a projection spaced from said hub, said switch including a switch arm, a pivot pin foi-'said switch arm having its ends mounted in said hub and said projection, a cover on said base member for said switch, and mounting screws for said cover projecting into said bracket and projection.

10. In a control switch, a base memlfier, a range adjusting shaft extending through said base member, a coiled bimetal element mounted on said shaft, a switch on said base member having an actuating element, an operative connection between said bimetal element and said actuating element, said base member having a hub for said adjusting shaft, a conduit fitting on one side of said hub, said switch being monuted on the other side of said hub, terminals for said switch mounted on opposite sides of Said hub between said switch and said conduit tting', said conduit fitting being adapted to connect' with a conduit carrying wires for connection with said terminals, a cover for said base member and switch, and a knob on said adjusting shaft, said cover having a dial for said knob.

ll. A control switch comprising a base member, a pair of base plates secured tc the bottom thereof to form a temperature responsive element housing, a range adjusting shaft extending through said base member and into such housing, a spiral bimetal element having its inner end connected to said shaft and located within such housing, a switch on said base member having an actuating element extending into such housing, an operative connection therein between the outer end of said bimetal element and said actuating element, said switch being mounted on one side of said shaft, a conduit litting mounted on the other side thereof and being adapted to connect with a conduit carrying wires for connection with said switch, and a knob on said adjusting shaft. j

i2. In acontrol switch, a base member, a pair of base plates secured to the bottom thereof to form a temperature responsive element housing, a range adjusting shaft extending centrally downward through said base member and into such housing, a coiled bimetal element mounted on said shaft within said housing, a switch on said base member having an actuating element extending into such housing, an operative connection between said bimetal element and said actuating element, a bracket secured to said base member, a conduit fitting connected therewith, said bracket having a perforation through which'said `adjusting shaft extends, said bracket beyond said shaft having anl upturned stop portion, a knob on said shafthaving an arcuate groove to receive said stop portion, said base .member having a hub for said `shaft and a projection spaced from said hub, said switch inifi cluding a switch arm between said hub andl said projection, a magnet to impart snap action to said switch arm, a pivot pin for said switch arm having its ends mounted in said hub and said projection, a cover on said base member for said switch, mounting screws for said cover 'project-- ing into said bracket and projection, said switch arm having a contact carried thereby, a mounting plate having another contact supported. thereby, said mounting plate spanning said hub and projection and having said other contact adjustable relative thereto to change the differential of operation of said switch by varying the distance of the switch arm relative to the magnet in closed circuit position of the switch.

A control switch comprising a base member, a range adjusting shaft through said base member, a bimetal element mounted on said shaft, a switch on said base plate having an actuating element operatively connected with said bimetal element, a knob on said shaft, said base member having a hub for said shaft and a projection spaced from said hub, said switch including a switch arm between said hub and said projection, a pivot pin for said switch arm having its ends mounted in said hub and said projection, said switch arm having a contact carried thereby, and a mounting plate having a contact supported thereby, said mounting plate spanning said hub and projection.

14. In a control switch, a base member, a range adjusting shaft extending through said base member, a bimetal element mounted on said shaft, a switch on said base plate having an actuating element operatively connected with said bimetal element, said switch including anarxn and a leaf spring having limited lost motion relative to said arm, a contact carried by said leaf spring, and a stationary contact for cooperation therewith.

15. lin a control switch, a base member, a range adjusting shaft extending through said 'base member, a bimetal element mounted on said shaft, a switch arm on said base plate having an actuating element operatively connected with said bimetal element, said switch arm having a leaf spring provided with limited lost motion relative said arm, a movable contact carried by said leaf spring, and a stationary contact for cooperation therewith, said stationary contact being adjustable to stop said movable contact and switch arm in a predetermined position 4to vary the diii'erential of operation of the switch.

16. In a control switch, a base member, a pair of base plates secured to the bottom thereof to form a temperature responsive element housing, a range adjusting shaft extending through said base member and into s uch housing, a bimetal element mounted on said shaft within said housing, means for securing one of said base plates to the surface of a pipe or the like to receive heat therefrom, a switch on said base plate having an actuating element extending into such housing, an operative connection between lsaid bimetal element and said actuating element, said l switch including a switch arm, a magnet for imparting snap action thereto, a movable contact carried by said switch arm, and a stationary contact for cooperation therewith, said stationary contact being adjustable to stop said movable contact and switch arm in a predetermined po-` sition relative to said magnet tovary the differential of operation of the switch.

BURTON E. SHAW. 

